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Vocal microphone feedback


tahiche
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Hi,

I'm working on some vocal patches. I'm using a standard sm58 mic into a mixer to Monitors. I'm impressed by the sound of the mic pre in the Helix and the Studio pre and blocks are great.

i have encountered a problem where I run into some bad feedback. It seems like it's happening when compressor and effects are chained. 

Im using path 1A and 1B for guitar (CGB), path 2A for bass (SubNUp octaver in fxloop) and 2N for vocals.

 

A typical vocal  chain would be:

studio pre (pretty much DEFAULT settings plus high and low cut) - LA Compressor - (optional) pitch block - (optional) modulation, phaser... - delay - reverb

 

i try to keep reverb and delays short, but occasionally pump it up for some parts. when I have a few blocks engaged I get some pretty bad feedback. It seems to build up right after I finish a phrase, and gets worse if I keep "breathing". It's somehow related to the compressor and maybe the reverb... Tried lowering the compressor ratio, higher threshold... it helps but basically because it makes the volume lower. So I think proper comp settings will help but I haven't been able to find a good spot.

I'm wondering if you nice and helpful people could point me in the right direction as in preamp settings, compression settings, etc so as to tame the feedback. I sort of tame it song by song by increasing height cuts and so on, but I'm not confident and don't feel too good about turning up at a venue and getting that embarrassing and horrible feedback. 

I also need to add distorsion to vocals, I'm holding back for the moment cos that is really going to make things worse. 

I own a Voicelive3 and had no problem with feedback. I believe VL3 has some feedback protection mechanism as well as adaptive compression, which I never gave much thought to but seems like it was a good feature.

 

Thanks!

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The Helix is not responsible for creating feedback, the way it is used is. If you over process a microphone, it will feedback. 

  • Start with good positioning of the mic to monitor. Make sure they are never looking at each other. 
  • Watch the gain staging to make sure distortion is not being introduced someone along the way
  • As you turn up, bad frequencies will introduce themselves. Learn to recognize them and notch them out. Always CUT bad frequencies, do not boost anything with the EQ.
  • Compressor.... try a 4:1 ratio, and attenuate the peaks by just a couple of db. It is gentle, but it makes a big difference. This will NOT add feedback unless you turn it up too loud. 
  • reverb and delay are like adding "spice" to food while cooking. A little goes a long, long way. If the reverb is delay is "taking off", the tail of the effect is turned up way too far. 
14 hours ago, tahiche said:

I own a Voicelive3 and had no problem with feedback. I believe VL3 has some feedback protection mechanism as well as adaptive compression, which I never gave much thought to but seems like it was a good feature.

 

IMO...  You are much better off learning how to control feedback on your own. Having a machine baby you through it just masks the problems that shouldn't be there to begin with. 

 

14 hours ago, tahiche said:

path 1A and 1B for guitar (CGB), path 2A for bass (SubNUp octaver in fxloop) and 2N for vocals.

 

 

I assume you mean 2B for vocals...

Since you running 3 paths, make sure they are isolated and not interfering with each other. If they bleed into each path (routing) it will cause problems.  

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11 hours ago, codamedia said:

IMO...  You are much better off learning how to control feedback on your own. Having a machine baby you through it just masks the problems that shouldn't be there to begin with. 

And right you are ;) 

Im getting there... My compression threshold was way too low, I was over compressing. I believe I had the default setting which is at around -46db. That's probably a good staring point for guitar, but too low for vocals. I set it to around -20db and things improved dramatically. I wish the Helix had some sort of a metering thingy... I fiddle with compressors and know the basics but I tend to rely on DAW metering and didn't realize it was so off. Maybe even the tail from the reverb (which wasn't too high) from the speakers was reaching the microphone and being compressed... that would explain the "feedback after words" scenario. 

Now that it's somehow under control I want to incorporate some distorsion, megaphone kind of sound. That'll probably let hell loose again. Any tips on how to incorporate distorsion on vocals?. I'm thinking compression after distorsion, or no compression at all... 

thanks for your help!

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11 hours ago, tahiche said:

Any tips on how to incorporate distorsion on vocals?. I'm thinking compression after distorsion, or no compression at all... 

 

You are on to something there. Distortion naturally compresses... so when you engage that, you might want to try disengaging the compressor. That can be done via snapshot, or even by applying both to the same footswitch so you toggle between them. 

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3 hours ago, codamedia said:

 

You are on to something there. Distortion naturally compresses... so when you engage that, you might want to try disengaging the compressor. That can be done via snapshot, or even by applying both to the same footswitch so you toggle between them

Sounds right. Any tip of what kind of compression block might be appropiate for vocals?. Maybe just cracking up the preamp?

Thanks

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8 hours ago, tahiche said:

Sounds right. Any tip of what kind of compression block might be appropiate for vocals?. Maybe just cracking up the preamp?

Thanks

 

The LA Studio Comp is the perfect compression block for vocals... just don't over compress. 

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8 hours ago, codamedia said:

The LA Studio Comp is the perfect compression block for vocals... just don't over compress

Thanks for the tip!. Any advice on setings, a starting point?.

I was using Deluxe comp as it has more "standard" parameters, specifically threshold, and seems like a "safer" approach. But i´d appreciate some general settings for the LA.

Overall i find compressors in Helix to be very "noticable" and thus you have to be careful. 

The thing that defeats me is the lack of meters in this scenario. I can´t seem to set the threshold reliably  by ear. Default compressor settings set the threshold at around -40db which seems like a lot to me... I actually have no idea of what kind of db´s i´m working with. When i sing my loudest am i over 0db?, i can´t even set the input gain reliabily without a meter or some sort of cliping indicator. 

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The LA Studio comp is based on an LA2A.... a two knob compressor, extremely easy to use, and sounds great. 

 

Load the default settings.... then concentrate on just two others. There are no "suggested settings" with this compressor... other than the defaults which are setup really well. 

  • Peak Reducation: Lower this to decrease compression, raise it to increase compression. The default setting is a great starting point, so just decrease/increase a little if needed. HINT: Once it starts compressing the volume will get quieter as you raise this... if you want a gentle compression start with a low setting and raise until you notice the first "drop" of volume, then back it back off a hair. 
  • Level: If you increase the "peak reduction" for heavy compression it will get quieter and you will need to increase the output level to compensate. With a gentle compression you should not need to change this at all.

The Peak Reduction is similar to the threshold on other compressors, but it also scales the ratio at the same time. 

 

With all compressors... the input gain produces the exact same results as lowering the threshold (or raising the peak reduction on the LA2A). The more input you send a compressor, the more it compresses. Not knowing the input level you feed the compressor makes it impossible to recommend specific settings. Read my  "hint" in the Peak Reduction for the closest thing I can give to a recommended setting. 

 

You are right... a peak reduction meter on the Helix would go a long way to assisting with this... I would just say "have the signal attenuate a couple DB's at most".

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Thanks!. Great tips. I've used emulations of this compressor in DAW environment. 

The thing is without a meter I have no clue of what kind of input I'm feeding the compressor. - 20DB, - 10db, 0db?. I guess I don't have the knowledge or experience without a meter. But in that case this compressor makes more sense as it's just "more or less" rather than a number which I have no clue about. 

If I connect my iPad via USB... Will y that measurement be reliable?. Will the USB audio reading be equivalent to that coming out of the xlr/jack outputs?. 

That way I could measure the before and after compression and see where I'm at... 

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  • 2 months later...

Why use a pre amp for vocals?

If you wouldn't use the Helix for vocals you would plug the mic directly to the table.

I'm not saying you shouldn't but are genuinely interested in the reason.

I use the Helix for some vocal effects and started at first with a pre amp but have changed to using none.

It works fine but I'm always wondering if I'm missing something

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15 hours ago, talwilkins said:

Why use a pre amp for vocals?

If you wouldn't use the Helix for vocals you would plug the mic directly to the table.

 

By table I'm assuming you mean the mixing board all of which have a pre amp on each input channel which is used to adjust the signal level of each input before each channel's faders.  That being said I don't know if you're gaining anything on the Helix if you're sending the combined guitar and vocal signal to the mixing board.

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  • 4 weeks later...

I usually read the forums and don't post - but I just wanted to throw in my comment that I have also removed the Studio Tube Pre block from my vocal chain because I found that through a PA system, my vocals sound better without it. I've been through many iterations and decided that it just isn't necessary. Agreed with the comment from @talwilkins that the output from the Helix will normally run into a mixing board that has a preamp anyways.

 

My setup: I set my mic input gain to +21db and my 1/4" line out (which runs to a DI box and out to XLRs that run to the board) to instrument level in global settings. The +21db of mic input gain was set such that the signal that my board receives from the DI box is identical to the signal that the board would receive if I had plugged my microphone in directly. This way, I can always plug my output into a mixer board and not have to worry about any issues with my level. Every block on my chain is then setup such that bypassing or engaging the block does not change the level of the output (i.e., all are set to unity gain when engaged).

 

With this setup, my vocals sound better without the Studio Tube Pre block. I should note that in headphones and at home with studio monitors the sound is fine, but through a large PA system, definitely better without the Studio Tube Pre. I suppose if you want a preamp color that you aren't getting from your mixer's preamps, you can use the Studio Tube Pre. For me, I found that using the Studio Tube Pre resulted in a gain-y tube-y sound that was a bit boomy and metallic - didn't sit well in the mix. My band plays stuff like Anberlin, Funeral for a Friend, Rise Against, Story of the Year, Thrice, Billy Talent, etc. I found a similar effect with the LA Studio Comp and in the next few days I'm going to test out the Deluxe Comp to see if it's a bit more transparent.

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I have my mic in gain at 9 dB

Not sure why actually but on the mixer I seem to have around the same level as the other mics that are connected directly to the mixer.

I go XLR out at mic level.

I do wonder why mic lever seems a lot quieter than the mic directly to the table (it seems about 9 dB but it could be a bit more or less)

As you can see I haven't gone very precise about this, no measurements.

It sounds fine.

Why use a compressor on voice?

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I usually use the multiband compressor but I’m only compressing under 300hz. Otherwise the boomy stuff and mud that’s not cut by the HPF can be a bit too dynamic. I also use the deluxe comp now with about -2db of compression. I’m now also running the LA Comp with full peak reduction but only about 10% mix (this basically works as a parallel compressor without needing to run a separate path). It works well for vocals that might be a bit more a aggressive and choppy, allowing you to be aggressive without sticking out too much from the rest of the band. Still learning, always learning!

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